import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import java.security.NoSuchAlgorithmException;
import java.security.Security;
/**
 * DES加密的，文件中共有两个方法,加密、解密
 * @author Lion
 * @author www.lionsky.net
 */
public class Des {
    private String Algorithm = "DES";
    private KeyGenerator keygen;
    private SecretKey deskey;
    private Cipher c;
    private byte[] cipherByte;


    /**
     * 初始化 DES 实例
     */
    public Des() {
          init();
    }


    public void init() {
        Security.addProvider(new com.sun.crypto.provider.SunJCE());
        try {
               keygen = KeyGenerator.getInstance(Algorithm);
               deskey = keygen.generateKey();
               c = Cipher.getInstance(Algorithm);
         }
         catch(NoSuchAlgorithmException ex){
            ex.printStackTrace();
        }
         catch(NoSuchPaddingException ex){
            ex.printStackTrace();
        }
       }


    /**
     * 对 String 进行加密
     * @param str 要加密的数据
     * @return 返回加密后的 byte 数组
     */
     public byte[] createEncryptor(String str) {
        try {
             c.init(Cipher.ENCRYPT_MODE, deskey);
             cipherByte = c.doFinal(str.getBytes());
        }
        catch(java.security.InvalidKeyException ex){
            ex.printStackTrace();
        }
        catch(javax.crypto.BadPaddingException ex){
            ex.printStackTrace();
        }
        catch(javax.crypto.IllegalBlockSizeException ex){
            ex.printStackTrace();
        }
        return cipherByte;
     }


    /**
     * 对 Byte 数组进行解密
     * @param buff 要解密的数据
     * @return 返回加密后的 String
     */
     public String createDecryptor(byte[] buff) {
        try {
           c.init(Cipher.DECRYPT_MODE, deskey);
           cipherByte = c.doFinal(buff);
        }
        catch(java.security.InvalidKeyException ex){
            ex.printStackTrace();
        }
        catch(javax.crypto.BadPaddingException ex){
            ex.printStackTrace();
        }
        catch(javax.crypto.IllegalBlockSizeException ex){
            ex.printStackTrace();
        }
        return (new String(cipherByte));
     }
}

